diff options
Diffstat (limited to 'drivers/spi/spi.c')
| -rw-r--r-- | drivers/spi/spi.c | 111 |
1 files changed, 111 insertions, 0 deletions
diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c index 2ec8e66a8098..34e3741504f9 100644 --- a/drivers/spi/spi.c +++ b/drivers/spi/spi.c @@ -144,6 +144,8 @@ SPI_STATISTICS_TRANSFER_BYTES_HISTO(14, "16384-32767"); SPI_STATISTICS_TRANSFER_BYTES_HISTO(15, "32768-65535"); SPI_STATISTICS_TRANSFER_BYTES_HISTO(16, "65536+"); +SPI_STATISTICS_SHOW(transfers_split_maxsize, "%lu"); + static struct attribute *spi_dev_attrs[] = { &dev_attr_modalias.attr, NULL, @@ -181,6 +183,7 @@ static struct attribute *spi_device_statistics_attrs[] = { &dev_attr_spi_device_transfer_bytes_histo14.attr, &dev_attr_spi_device_transfer_bytes_histo15.attr, &dev_attr_spi_device_transfer_bytes_histo16.attr, + &dev_attr_spi_device_transfers_split_maxsize.attr, NULL, }; @@ -223,6 +226,7 @@ static struct attribute *spi_master_statistics_attrs[] = { &dev_attr_spi_master_transfer_bytes_histo14.attr, &dev_attr_spi_master_transfer_bytes_histo15.attr, &dev_attr_spi_master_transfer_bytes_histo16.attr, + &dev_attr_spi_master_transfers_split_maxsize.attr, NULL, }; @@ -2237,6 +2241,113 @@ struct spi_replaced_transfers *spi_replace_transfers( } EXPORT_SYMBOL_GPL(spi_replace_transfers); +int __spi_split_transfer_maxsize(struct spi_master *master, + struct spi_message *msg, + struct spi_transfer **xferp, + size_t maxsize, + gfp_t gfp) +{ + struct spi_transfer *xfer = *xferp, *xfers; + struct spi_replaced_transfers *srt; + size_t offset; + size_t count, i; + + /* warn once about this fact that we are splitting a transfer */ + dev_warn_once(&msg->spi->dev, + "spi_transfer of length %i exceed max length of %i - needed to split transfers\n", + xfer->len, maxsize); + + /* calculate how many we have to replace */ + count = DIV_ROUND_UP(xfer->len, maxsize); + + /* create replacement */ + srt = spi_replace_transfers(msg, xfer, 1, count, NULL, 0, gfp); + if (!srt) + return -ENOMEM; + xfers = srt->inserted_transfers; + + /* now handle each of those newly inserted spi_transfers + * note that the replacements spi_transfers all are preset + * to the same values as *xferp, so tx_buf, rx_buf and len + * are all identical (as well as most others) + * so we just have to fix up len and the pointers. + * + * this also includes support for the depreciated + * spi_message.is_dma_mapped interface + */ + + /* the first transfer just needs the length modified, so we + * run it outside the loop + */ + xfers[0].len = min(maxsize, xfer[0].len); + + /* all the others need rx_buf/tx_buf also set */ + for (i = 1, offset = maxsize; i < count; offset += maxsize, i++) { + /* update rx_buf, tx_buf and dma */ + if (xfers[i].rx_buf) + xfers[i].rx_buf += offset; + if (xfers[i].rx_dma) + xfers[i].rx_dma += offset; + if (xfers[i].tx_buf) + xfers[i].tx_buf += offset; + if (xfers[i].tx_dma) + xfers[i].tx_dma += offset; + + /* update length */ + xfers[i].len = min(maxsize, xfers[i].len - offset); + } + + /* we set up xferp to the last entry we have inserted, + * so that we skip those already split transfers + */ + *xferp = &xfers[count - 1]; + + /* increment statistics counters */ + SPI_STATISTICS_INCREMENT_FIELD(&master->statistics, + transfers_split_maxsize); + SPI_STATISTICS_INCREMENT_FIELD(&msg->spi->statistics, + transfers_split_maxsize); + + return 0; +} + +/** + * spi_split_tranfers_maxsize - split spi transfers into multiple transfers + * when an individual transfer exceeds a + * certain size + * @master: the @spi_master for this transfer + * @message: the @spi_message to transform + * @max_size: the maximum when to apply this + * + * Return: status of transformation + */ +int spi_split_transfers_maxsize(struct spi_master *master, + struct spi_message *msg, + size_t maxsize, + gfp_t gfp) +{ + struct spi_transfer *xfer; + int ret; + + /* iterate over the transfer_list, + * but note that xfer is advanced to the last transfer inserted + * to avoid checking sizes again unnecessarily (also xfer does + * potentiall belong to a different list by the time the + * replacement has happened + */ + list_for_each_entry(xfer, &msg->transfers, transfer_list) { + if (xfer->len > maxsize) { + ret = __spi_split_transfer_maxsize( + master, msg, &xfer, maxsize, gfp); + if (ret) + return ret; + } + } + + return 0; +} +EXPORT_SYMBOL_GPL(spi_split_transfers_maxsize); + /*-------------------------------------------------------------------------*/ /* Core methods for SPI master protocol drivers. Some of the |